As a device for controlling the opening and closing timing of the intake valve or the exhaust valve of an engine, there has been proposed, for example, a phase variable device structured so that a sprocket to which a driving force of a crankshaft of the engine is transmitted and a camshaft that forms a valve train rotate in an integrated manner, and the sprocket and the camshaft rotate in synchronization, but when an electromagnetic brake unit causes a braking force to act on a rotary drum, a rotational delay occurs in the rotary drum with respect to the sprocket, and in connection with the rotational delay of the rotary drum, the phase of the camshaft with respect to the sprocket changes (refer to Patent Document 1).
In this phase variable device, since adopted is a structure where an engine oil is introduced to a relative sliding portion between a friction material of a clutch case and the rotary drum via an oil passage provided in the camshaft, an oil reservoir provided radially inside of the clutch case, and a cutout for oil introduction provided at a front edge portion of an inner peripheral wall of the clutch case, a relative sliding surface between the friction material and the rotary drum can be cooled.    Patent Document 1: Japanese Published Unexamined Patent Application No. 2002-371814 (Refer to page 4 to page 6, and FIG. 1 to FIG. 4.)